Curvature fluctuations of fluid vesicles reveal hydrodynamic dissipation within the bilayer

• 成果类型: Article
• 署名作者: Faizi, Hammad A.; Granek, Rony; Vlahovska, Petia M.
• 署名单位: Northwestern University; Ben-Gurion University of the Negev; Ben-Gurion University of the Negev; Northwestern University; Northwestern University; University of Chicago
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-12766
• DOI: 10.1073/pnas.2413557121
• 发表日期: 2024-10-29
• 关键词: membrane fluctuations; dynamic fluctuations; shape fluctuations; mechanisms; SCATTERING

摘要

The biological function of membranes is closely related to their softness, which is often studied through the membranes' thermally driven fluctuations. Typically, the analysis assumes that the relaxation rate of a pure bending deformation is determined by the competition between membrane bending rigidity and viscous dissipation in the surrounding medium. Here, we reexamine this assumption and demonstrate that viscous flows within the membrane dominate the dynamics of bending fluctuations of nonplanar membranes with a radius of curvature smaller than the Saffman-Delbr & uuml;ck length. Using flickering spectroscopy of giant vesicles made of dipalmitoylphosphatidylcholine, DPPC:cholesterol mixtures and pure diblockcopolymer membranes, we experimentally detect the signature of membrane dissipation in curvature fluctuations. We show that membrane viscosity can be reliably obtained from the short time behavior of the shape time correlations. The results indicate that the DPPC:cholesterol membranes behave as a Newtonian fluid, while the polymer membranes exhibit more complex rheology. Our study provides physical insights into the time scales of curvature remodeling of biological and synthetic membranes.